Specific reaction of α,β‐unsaturated carbonyl compounds such as 6‐shogaol with sulfhydryl groups in tubulin leading to microtubule damage

6‐Shogaol and 6‐gingerol are ginger components with similar chemical structures. However, while 6‐shogaol damages microtubules, 6‐gingerol does not. We have investigated the molecular mechanism of 6‐shogaol‐induced microtubule damage and found that the action of 6‐shogaol results from the structure of α,β‐unsaturated carbonyl compounds. α,β‐Unsaturated carbonyl compounds such as 6‐shogaol react with sulfhydryl groups of cysteine residues in tubulin, and impair tubulin polymerization. The reaction with sulfhydryl groups depends on the chain length of α,β‐unsaturated carbonyl compounds. In addition, α,β‐unsaturated carbonyl compounds are more reactive with sulfhydryl groups in tubulin than in 2‐mercaptoethanol, dithiothreitol, glutathione and papain, a cysteine protease.